CONTAGIOUS DISEASES OF METALS.

Otago Witness, Issue 2983, 17 May 1911, Page 93

CONTAGIOUS DISEASES OF METALS.

Some years ago scientific men in Russia were astonished (says the New York Outlook), to find that some bars of pure tin which, had lain a long time in a warehouse had! turned from a white metal into a pile of grey powder. An .analysis of the powder showed it to be as pure tin as were the bars. Scientists were unable to determine the cause, of this disintegration, and researches have been carried on ever since in an endeavour to ascertain it. Professor Ernest Cohen, of the University of Utretoht, published the result of his researches in “La Technique ” in 1910. He found that the “ disease ” was not confined to pig tin, but occasionally attacked organ pipes of tin, and that the same cause, or something similar, produced disintegrations in lead and copper, and in their alloys. He was unable to determine the cause, but found that the action took place only within certain circumscribed temperatures ; that by keeping the tin in a very low temperature for a long time it was gradually converted into the grey powder and, conversely, that by keeping the grey powder at a temperature of about 80deg for some time it returned to the normal white condition. He found likewise that the change in other metals was due to an alteration from an amorphous into a crystalline condition jbut in his researches, he discovered the most interesting facts —that the tin especially might resist the action of the low temperature unless “inoculated ” with some of the grey powder ; that as soon as the tin was brought in contact with some of the powder the metal began to swell and to disintegrate, and that the “ disease extended until the whole mass was changed; and that the process strangely like that of “ infection, which gives rise to some of the diseases of plants and animals. Experimenting with other metals, he found that if the product of their alteration came in contact with sheets of copper or lead or polished rolls or many alloys, the disintegration commenced at the point of contact, and rapidly extended, and that this took place at any temperature. Professor Cohen recommended that valuable metallic objects in museums, etc., should be carefully inspected from .time to time, and that if any indicated that they were “ infected they should be immediately removed from the case containing other metals, and that, as temperature has much to do with the phenomena, it should not be allowed to fall below 70deg. In the article entitled “The Search for the Origin of Life,” which was published in the Outlook of December 31, 1910, the writer, Dr Ledoux, mentioned the fact that the processes of crystallisation and of amorphous growth in mineral substances in some cases resembled very closely the process of growth of organic matter through cell multiplication. It would seem from the latest report of Professor Cohen, which is published in a recent number of the French journal, Metaux et Alliagos, that no created thing is immune from “ disease,” consides°d independently of the ordinary chemical processes of oxidation, reduction, etc.